Throttle grip: Remove bar end. Loosen the control housing bolts. Loosen the throttle cable adjuster. Remove throttle cable barrells from recessed carriers. Separate control housing. Remove grip. Replace with new grip. Re-install all components.
Left grip: Remove bar end. Squirt WD40 or other lubricant into grip. Wiggle and pull until removed. Clean bar. Install new grip and tighten allens. Reinstall bar end.
Should take about 15 minutes.